Follicles were collected from ovaries removed under halothane anaesthesia from 7 rhesus monkeys. Follicle and ovum diameters were measured and chromatin organization was determined by fluorescence microscopy. The relative growth curve of oocytes and follicles using a loess regression technique displayed a triphasic curve. The relationship of follicle and oocyte growth and oocyte maturation (perinucleolar chromatin configuration) was analyzed. Chromatin organization progressed in relation to ovum size. In terms of follicle size, oocytes first respond (past the unrimmed nucleolar stage) during the period of earliest antrum formation, then the response remains relatively the same until the follicle reaches 600 m when the majority of responders are at the partial rim stage. But it is not until the follicle has reached a diameter beyond 1000 m that the majority of oocytes are at the fully rimmed stage (meiotically competent).